1. Field of the Invention
This invention relates to instruments for use in dentistry. More particularly, the invention relates to a device for manipulating dental restorations such as thin ceramic veneers which are intended to be laminated and adhered to the outer or labial surfaces of teeth, and crowns and bridges used to cap or replace missing teeth.
2. Description of Background Art
For a variety of reasons, the enamel surfaces of teeth sometimes become permanently stained. Prolonged use of the antibiotic tetracycline, for example, can permanently discolor the teeth. The degree of discoloration of the enamelled surface of teeth can in some cases be sufficient to produce a highly unsightly effect.
The appearance of badly discolored teeth can have a detrimental effect upon the self-image of a person afflicted with this condition, and can adversely affect both business and social relations of the individual. With these factors in mind, dental health care professionals have developed a technique for treating severely discolored teeth.
In a procedure referred to as cosmetic bonding, a thin veneer of ceramic having a shape and curvature matching the outline shape and surface curvature of a discolored tooth is laminated to the tooth by cementing the veneer to the outer or labial surface of the tooth, after the tooth has been specially prepared. The veneer has a surface coloration and gloss which duplicate that of the individual's healthy teeth. Also, the veneer is sufficiently opaque to mask the stained surface of the underlying tooth. By this procedure the individual's teeth may be restored to a pleasant appearing, healthy state.
The brief description of the cosmetic bonding of ceramic veneers to teeth given above does not convey an appreciation for the complexity and delicacy of the actual veneering procedure. In a sequence of steps requiring exercise of a substantial degree of artistic craftsmanship, the dentist must prepare each tooth to receive a ceramic veneer, and make accurate impressions of the prepared teeth. Teeth impressions are made by forming a semi-liquid dental impression material over the teeth and allowing the material to harden. The impressions are then used by a highly skilled dental ceramist, or the dentist himself, to make molds in which the required ceramic veneers are eventually cast. Each cast veneer is individually fabricated and must have the precise dimensions, coloration, luster and opacity.
The number of individually demanding steps required to fabricate each ceramic tooth veneer for cosmetic bonding results in a substantial investment in time having been expended in the production of each finished veneer. Thus, the replacement value of each custom-made veneer is high. Accordingly considerable care must be exercised in handling a veneer to avoid damaging the veneer.
Since a typical veneer has a thickness range of 0.3 mm. to 4 mm., and an average thickness of about 0.5 mm., the veneer is relatively fragile until it has been cemented (laminated) to and supported by the tooth for which it was custom fabricated to laminate.
Finished ceramic veneers are attached to the teeth by means of a light sensitive adhesive. After a number of preparation steps, each of the veneers to be laminated to one or a group of teeth is temporarily fastened to the appropriate tooth. The purpose of the temporary fitting is to check size, opacity, and coloration of each of the veneers. After this preliminary fitting, each of the veneers is removed, and both veneer and tooth thoroughly cleaned of the temporary adhesive (usually glycerine) used to hold the veneer to the tooth. The outer surface of the tooth is then coated with a light-sensitive photopolymeric adhesive, and a ceramic veneer placed in position on the tooth. Usually, this placement is done by means of the dentist's fingers. Typically, an assistant then irradiates the outer surface of the ceramic veneer with a small, intense light source. Light transmitted through the ceramic veneer causes a photo-chemical reaction to occur in the light-sensitive adhesive, causing it to harden.
During the light-exposure process, which takes between 20 and 60 seconds, the dentist must hold the veneer in a precisely aligned position with respect to the outer surface of the tooth. If the veneer is displaced even slightly from its aligned position during the adhesive setting process, the ceramic veneer must be ground off of the tooth, and a replacement veneer fabricated.
Because of the cost and fragility of ceramic tooth veneers, and the precision with which they must be placed on a tooth in the lamination process, it would seem desirable to provide a device for holding and manipulating a ceramic veneer, especially during the placement of the veneer on a tooth during the adhesive bonding of the veneer to the tooth. Some relatively complex vacuum holding devices have been proposed for use with ceramic dental veneers. However, a need for an efficient, low-cost device for manipulating ceramic dental veneers was perceived by the present inventor, and was a motivating factor in the development of the present invention. Some versions of the present invention are also useful for installing crowns or bridges in the mouth of a patient.